1. Field of the Invention
The present invention relates to an information processing apparatus and an information processing method. More particularly, the invention relates to an information processing apparatus and an information processing method used advantageously to carry out encoding.
2. Description of the Related Art
Picture compression systems, of which the MPEG (Moving Picture Coding Experts Group/Moving Picture Experts Group) is a representative standard, accomplish high degrees of data compression efficiency by compression-encoding video signals through inter-frame prediction.
Under the MPEG standard, there is a compression encoding system called Long-GOP (Group of Pictures) compression which utilizes bidirectional inter-frame prediction involving three picture types: I-picture, P-picture and B-picture.
The I-picture is short for an intra coded picture. Coded independently of other pictures, the picture can be decoded using information about this picture alone. The P-picture is short for an inter-frame forward predictive coded picture that is expressed by the differential relative to the temporally preceding frame (i.e., in forward direction). The B-picture is short for a bidirectionally predictive coded picture. This picture is coded through motion compensation inter-frame prediction using the temporally preceding (forward) or subsequent (backward) picture, or both the preceding and the subsequent pictures (bidirectional).
In a video editing setup, the pictures compressed through inter-frame prediction are subject to the constraints of relations of predictive compressed signals between the frames involved. That means video materials may not be spliced using the predictive compressed video signals. Thus most systems designed in advance to edit video materials perform their coding through intra-frame compression and dispense with inter-frame prediction.
However, where video signals involving huge quantities of high-resolution video information (e.g., HD (high definition) signals) are handled, coding through intra-frame compression alone yields low degrees of compression efficiency. If it is desired to send or store large quantities of data, intra-frame compression coding can thus result in low transmission speeds, large storage capacities required, and other related disadvantages. That in turn necessitates implementation of an expensive system capable of high-speed processing. In other words, inexpensive systems for handling video signals of high-resolution video information in large quantities should preferably raise their compression efficiency through the use of inter-frame prediction.
There already exist techniques for editing MPEG streams. According to one such technique (e.g., PCT Patent Publication No. WO99/05864), coded pictures in the vicinity of edit points (splicing points) are temporarily decoded so that the video signals in uncompressed form are spliced at the edit points, before the pictures are again encoded. According to another such technique (e.g., Japanese Patent Application No. Hei 10-178645), frames are each split into portions before they are encoded in order to implement high-speed coding.